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Women's Health Magazine
Are You Misdiagnosing Sacroiliac Joint Dysfunction?
How to identify and treat this common form of back pain
By Michael R. Moore, M.D.
Low back pain is the second most common reason for visits to physicians and the most common reason for missing work. Most cases of acute back pain are self-limited and will resolve with a short period of rest, treatment with non-steroidal ant--inflammatory drugs (NSAIDs), and appropriate physical therapy. However, chronic disabling back pain requires a specific diagnosis for appropriate treatment.
Many physicians find the evaluation of low back pain frustrating because of the perceived difficulty in obtaining a specific diagnosis. Missed diagnoses of treatable conditions can lead to in appropriate surgery, chronic pain behavior, and narcotic dependence-all of which can have a catastrophic impact on the quality of the patient's life and can produce unnecessary expense for the health care system.
Sacroiliac joint pathology is an often-overlooked part of the differential diagnosis of low back pain and sciatica. New developments in interventional radiology are now allowing greater precision in the diagnosis of sacroiliac joint dysfunction. This enhanced diagnostic ability should lead to improved outcomes and early intervention, thereby avoiding the negative consequences associated with misdiagnosis.
This article will present a case report in which sacroiliac joint dysfunction was initially misdiagnosed. It will then detail the diagnosis and treatment of sacroiliac joint dysfunction and discuss why this condition might be unfamiliar to physicians.
Because of the difficulty in evaluating low back pain, many patients are labeled "hysterical" when, in fact, organic pathology exists. Studies have shown that women are more likely than men are to be viewed as neurotic when presenting with pain complaints. This fact, coupled with the fact that sacroiliac joint dysfunction is twice as common in women as it is in men, makes sacroiliac joint dysfunction a significant women's health issue, as the following true story demonstrates.
The patient was a 23-year-old woman experiencing severe and disabling left-sided low back pain with diffuse radiation to the left lower extremity; her symptoms had begun following a motor vehicle accident three years before. She had seen multiple practitioners in the past for these complaints. Repeated trials of physical therapy and NSAIDs had been ineffective, as had epidural steroid and trigger point injections. Magnetic resonance images (MRI), plain films, and a computed tomographic myelogram of the lumbar spine were all interpreted as normal.
The patient had been told that her pain pattern was "hysterical," that no organic pathology could explain her symptoms, and that the pain was "in her head." She had been referred for psychiatric evaluation and had been through a chronic pain program. She had been accused of "doctor shopping" and drug-seeking behavior.
When seen, she was taking 5 mg of hydrocodone bitartrate four times a day, and 25 mg of amitriptyline hydrochloride at bedtime. She had discontinued her work as a cosmetologist and as a part-time aerobics instructor. The patient described her pain as originating at the left posterior superior iliac spine and radiating to the groin and the entire left lower extremity. Maneuvers that stressed the left sacroiliac joint reproduced her typical pain.
She was referred for a fluoroscopically directed injection of local anesthetic (2 to 3 mL) into the synovial portion of the left sacroiliac joint. Thirrty minutes after the injection, she was pain-free for the first time in three years. However, her symptoms returned six to eight hours afterwards.
A diagnosis of sacroiliac joint dysfunction was confirmed. After undergoing a sacroiliac arthrodesis, the patient experienced complete resolution of both leg and low back symptoms. She retuned to work as a cosmetologist and resumed her activities as an aerobics instructor.
History: Approximately 80% of patients with sacroiliac joint dysfunction can identify a specific episode of trauma that initiated symptoms. The trauma, however, often seems too minor to cause a persistent and severe problem. A typical injury results from lifting a heavy object with a twisting motion, such as removing a suitcase from a car trunk. Another common mechanism of injury is a slip and fall. When the history contains these or similar injuries, and symptoms remain without progressive improvement, a specific evaluation for sacroiliac joint dysfunction should be considered.
In about 20% of cases, no specific traumatic episode is recalled, and the onset of symptoms is described as insidious. When there is no history of a traumatic episode, rheumatologic disorders-such as ankylosing spondylitis-should be excluded before a diagnosis of sacroiliac joint dysfunction is entertained.
Physical examination: Patients with sacroiliac joint dysfunction can present with signs and symptoms that are very similar to those of intervertebral disc disease. Many patients have pain confined to the area of the sacroiliac joint. Others have pressure on the S1 nerve and pain following the distribution of that pressure, in a pattern known as the pseudo S1 pattern. Physicians frequently assume that a patient with this pain pattern has L5-S1 disc herniation, and they may order an MRI to confirm the diagnosis of herniation. If the MRI is negative, they may conclude that the patient has a somatoform disorder. However, the presence of a sacroiliac joint disorder should be considered.
Diffuse pain radiating to the entire lower extremity is present in approximately 25% of patients with sacroiliac joint dysfunction. In the past, this pain pattern has been thought to represent a nonorganic or hysterical pattern.
Various physical examination maneuvers have been used to identify a sacroiliac origin of pain. Patrick's test, also known as the FABER test (for flexion, abduction, and external rotation) is probably the best known. Another commonly employed maneuver is Gaenslen's test, which includes hyperextension of the hip. Recent information has shown that such screening tests are not reliable in identifying pathology of sacroiliac joint.
The single feature consistently found among patients with sacroiliac joint dysfunction is pain location; when asked to point to where the pain seems to be originating, patients point to the area immediately around the posterior superior iliac spine. Thus, dysfunction of the sacroiliac joint should be considered in any patient complaining of pain in this area, even if the various traditional physical examination maneuvers are negative.
Confirmation: Diagnosis of sacroiliac joint dysfunction can be confirmed with a diagnostic injection performed by a physician skilled in the technique. Blind injections into the area of the sacroiliac joint are inadequate. Fluoroscopy or computed tomography guidance is necessary to ensure that the injectant is administered to the correct area.
The injection should involve the placement of a small volume (1 to 3 mL) of local anesthetic into the synovial portion of the joint. Correct placement is verified by the inclusion of contrast material in the injectant, which should outline the synovial portion of the joint. Large-volume injections or injections into the ligamentous portion of the joint will extravasate into the region of the lumbosacral plexus and can produce both false-negative and false-positive results.
The patient maintains a pain diary, in which he or she records the pain level immediately before and at regular intervals after the injection. Clear-cut relief of typical symptoms for a duration consistent with the action of the local anesthetic confirms the diagnosis.
Treatment: Patients with mild symptoms can usually be treated by conservative means. NSAIDs or a sacroiliac belt may be helpful. Mooney has reported success with a specific physical therapy protocol using resistive torso rotation exervises. When conservative measures fail and symptoms are disabling, a surgical fusion of the sacroiliac joint is an effective option in appropriately selected patients.
Many orthopedic surgeons and neurosurgeons have little experience or background in sacroiliac fusions, and much misinformation exists about the magnitude of the surgery. A typical sacroiliac fusion takes about one hour and requires a 24- to 48-hour hospitalization. The patient must bear no weight on the operated side for two months and must use crutches for ambulation.
In nonsmoking patients with no prior back surgery and no coexistent spine pathology, success rates are around 90%.
Smoking appears to have a significant deleterious effect on postoperative healing; the fusion may fail or pseudarthrosis may occur, which can allow the patient's pain to continue. In the largest reported series to date, no vascular or neurologic complications have been observed in 110 patients. Note that pseudoarthrosis, the biggest risk of surgical fusion of the sacroiliac joint, is almost exclusively limited to patients who are smokers.
Theoretically, fusion of the sacroiliac joint might prevent the pelvis from expanding enough to allow normal vaginal delivery. Little information exists on this topic. In my experience, one patient with sacroiliac fusion subsequently had two uncomplicated pregnancies that each resulted in normal spontaneous vaginal deliveries. Only one other patient with a sacroiliac fusion has become pregnant, and this patient underwent an elective cesarean section after consultation with her obstetrician. The potentially increased need to deliver by cesarean section should be discussed with any woman of childbearing age who is considering a surgical fusion of the sacroiliac joint.